HI Dr Who!
The name should be "Doctor Who". Anyhow, that is not really much information to guess. There are many reasons why the cooling might not work as expected. One of them, and may be the most likely one is that the dew point sensor measuring the condensation of water on your heat pipes is activated and shuts down your active cooling.
The other reason is, that the control of active cooling is using the same hysteresis as the heating - which is +2K for on and -4K for with standard settings. This means, that the cooling starts with measured temperatures in the secondary circuit of 22°C and cools down to 16°C which is often already below the dew point. The problem here is that the hysteresis is just to large to allow for an effective cooling.
However, reducing the hysteresis is not so simple and requires some knowledge, since it requires to switch between temperature sensors, which in return requires further adjustments to the heating and cooling characteristics. But even after this change it is unlikely that you reach 21°C with a active cooling system, because it is just not an AC and missing the major effect of dehumidifying.
Anyhow, my suggestion is to ask your installation company to fix the issue and setup the cooling sufficiently.
Best regards
Gwyn
